Study Setting: Hospital EHR systems were categorized into five levels (Level_0 to Level_4) based on use of eight clinical applications. Level_3 systems can meet 2011 EHR “meaningful use” objectives. Process quality was measured as composite scores on a 100-point scale for heart attack, heart failure, pneumonia, and surgical care infection prevention. Statistical analyses were conducted using fixed effects linear panel regression model for all hospitals, hospitals stratified on condition-specific baseline quality, and for large hospitals.

Principal Findings: Among all hospitals, implementing Level_3 systems yielded an incremental 0.35–0.49 percentage point increase in quality (over Level_2) across three conditions. Hospitals in bottom quartile of baseline quality increased 1.16–1.61 percentage points across three conditions for reaching Level_3. However, transitioning to Level_4 yielded an incremental decrease of 0.90–1.0 points for three conditions among all hospitals and 0.65–1.78 for bottom quartile hospitals.